Pilot won't stay lit

[1947Steve]

I have (2) Mendota fireplace inserts. Model D40 Seabrook and Model DXV 42. They both have the same parts list. I keep having to replace the thermocouple and thermopile. I have propane. They only last a year or so then need to be replaced. I know that there is a HD thermocouple but that doesn't seem to make any difference. They are expensive also. Is there any aftermarket replacement for the following items and model numbers.

05-07-00061 Thermopile
05-07-00084 Thermocouple (HD for propane)

[gasguy]

Have a pro come do a service and have him adjust the pilot so the millivolt output is a little above the dropout point and still gives safe and reliable burner light off. Bigger is not always better for pilots with LP.

[1947Steve]

I did have a tech come over and he adjusted the milivolt reading as low as he could for the pilot flame. I talked to the factory tech last week and he indicated the service life on the HD thermocouple is in the neighborhood of 18 months. That seems like the parts are not up to par as I gave big money for the two units and certainly that seems to be labor and parts intensive. Was wondering if there are any aftermarket parts available? Also, is there a kit available for these units that would make them pilotless ignition? Thanks!

[1947Steve]

I live in Indiana and use them for heat in two different rooms. That is the reason I purchased those models as they put out alot more BTU's than the ones you get at Lows, etc.

[Cosmicmuffin]

My dad bought his home in 1957.,I pulled the furnace last year {Chrysler) still hade the original thermo couple in it, He claimed he never turned it off.That way it would not rust up etc. How can u argue with that!

[trouble time]

I am on propane and my thermo couple is 15 years old. It is not the original one, the first only lasted 5 years.
I would have a pro look at the set up and see if there are other factors effecting the thermo couple.

[darthvader]

flame strength(the right orifice, or dirt?) can effect the thermopile and thermocouple quite a bit. The big one(thermopile) is for operating the main burner, so if it's your pilot that keeps going out it's the thermocouple not the thermopile.

make sure your pilot has a nice blue flame that completely surrounds the the thermocouple with the unit running.